Force purity generally makes people feel sick, they have a hard time breathing first off, sweat gets in the victims eyes so they cant see, and then they start feeling sick, then they think they're fucking dying, and in doing so, the victim generally "fucking" kills themselves. Though this was probably Darth Slipknot's most versatile power in his arsenal. The possible effects are countless when using this power, in fact he used this if someone refused to buy lekku when he was a lekku thief at age 5.